The electric mat switch of the present invention is concerned with treadles and floor mat devices responsive to persons walking, stepping or dropping articles on the mat for closing a switch in an electric circuit. Specifically, the instant mat switch has been primarily developed and employed in association with robots, being responsive to the movement of persons or things into dangerous proximity with respect to an operating robot, to shut down the same. Of course, the instant mat switch is capable of many varied applications, all of which are intended to be comprehended herein.
Heretofore, the requirement of high sensitivity in a mat switch was incompatible with long term durability, as high sensitivity involved flexibility of parts which necessarily reduced strength and resistance to wear.
Illustrative of the prior art of which applicant is aware are the below listed patents:
______________________________________ U.S. PAT. NO. PATENTEE ______________________________________ 3,243,540 Miller 3,462,885 Miller 3,754,176 Miller 4,137,116 Miller 4,200,777 Miller 4,349,710 Miller ______________________________________
In prior art switches of this general type, there was required a highly localized deflection to operate the switch. Even a substantial force or weight may not have been sufficient to actuate a prior art switch, if the force or weight was distributed over a substantial area. In an attempt to obviate this problem, prior art devices often included internal protrusions for locally enhancing internal forces reacting to an external weight. This structure added to cost of materials, complexity of manufacture, and often inhibited or reduced flexibility to require additional space in shipping and storage.